EP3431925A1 - Road finisher with layer thickness detection device and method for detecting the thickness of an installed material layer - Google Patents

Abstract

A paver comprises a screed (16) for incorporating a layer of material (42) on a substrate (14) and a layer thickness detecting device for detecting the thickness (h B) of the incorporated layer of material (42). The layer thickness detection device comprises a first sensor (38) for detecting a first distance to the built-in material layer (42) and a second sensor (40) for detecting a second distance to the ground (14). The layer thickness detection device is firmly attached to the screed (16).

Description

The present invention relates to a paver, in particular a paver with a layer thickness detecting device and a method for detecting the thickness of a built-in by such a paver on a substrate material layer.

In general, a paver with a tracked chassis runs on a prepared ground on which a road surface to be produced or a road surface to be produced is to be applied. As a rule, the built-in road surface is a bituminous material, but also sandy or stony layers or concrete layers can be installed. In the direction of travel behind the paver a height-adjustable screed is provided at the front of a stockpile of the pavement material is accumulated, which is promoted and distributed by a conveyor, which ensures that on the front of the screed always a sufficient, but not too large amount the paving material is kept stockpiled. The height of the trailing edge of the screed opposite the surface of the prepared ground, which may optionally also be formed by an old pavement, defines the thickness of the finished pavement prior to its subsequent further consolidation by rolling. The screed is held on a pulling arm, which is rotatably mounted about a arranged in the central region of the paver traction point, the altitude of the screed is set by a Hydraulikverstelleinrichtung.

Fig. 1 shows a well-known paver, such as in the EP 0 542 297 A1 is described. The paver is designated in its entirety by the reference numeral 10 and includes a tracked chassis 12 with which the paver 10 travels on the prepared ground 14. At the rear end of the paver 10 in the direction of travel, a height-adjustable screed 16 is arranged, which is articulated by means of a pulling arm 18 at a traction point 20 on the paver 10. In front of the screed 16 there is a supply 22 of the asphalt material, whereby this supply is kept constant by means of a corresponding, known per se regulation of the speed of a screw-like conveyor 24 substantially over the entire width range of the screed 16. The screed 16 Floats on the asphalt of the road surface to be finished. The thickness of the road surface to be manufactured before its final consolidation by road rollers is adjusted by regulating the altitude of the trailing edge 26 of the screed 16. This height control is effected by changing the angle of attack of the screed 16, and is typically done by the control of actuating cylinders which engage the front ends of the tension arms 18. The paver comprises three ultrasonic sensors 28, 30, 32, which are fastened to a holder 34. The bracket 34 is attached to the pull arm 18. The three ultrasonic sensors 28, 30, 32 serve to scan a reference surface, which may be formed, for example, by an already manufactured or old web of the road surface.

When building a road, it is desirable to measure the generated layer as continuously as possible and in real time. The determination of the layer thickness is desired, for example, to control the quality of the newly installed road surface. If the calculated layer thickness, for example a bituminous layer, is too low, then there is a risk that the road surface breaks up early, which results in costly repairs of the road surface. On the other hand, the layer thickness should be checked with regard to the amount of material used in order not to obstruct too much material, which would lead to increased costs.

Known system for determining the layer thickness of a newly installed road surface, for example, in the EP 2 535 456 A1 , the EP 2 535 457 A1 or the EP 2 535 458 A1 described. A disadvantage of these known systems is that they are complex in terms of mechanical and signal processing technology and yet do not have sufficient accuracy in determining the layer thickness.

The object of the present invention is to provide an improved approach for determining the layer thickness of a built-in material by a paver material layer, which is less expensive, and which makes it possible to determine the layer thickness with increased accuracy.

This object is achieved by a paver according to claim 1, and by a method according to claim 15.

• einer Bohle zum Einbau einer Materialschicht auf einem Untergrund; und
• einer Schichtdickenerfassungsvorrichtung zum Erfassen der Dicke der eingebauten Materialschicht,
• wobei die Schichtdickenerfassungsvorrichtung einen ersten Sensor in Fahrtrichtung hinter der Bohle zum Erfassen eines ersten Abstands zu der eingebauten Materialschicht und einen zweiten Sensor in Fahrtrichtung vor der Bohle zum Erfassen eines zweiten Abstands zu dem Untergrund umfasst, und
• wobei die Schichtdickenerfassungsvorrichtung fest an der Bohle befestigt ist.

The present invention provides a paver with:

• a screed for installing a layer of material on a substrate; and
• a film thickness detecting device for detecting the thickness of the built-in material layer,
• wherein the layer thickness detection device comprises a first sensor in the direction of travel behind the screed for detecting a first distance to the built-in material layer and a second sensor in the direction of travel in front of the screed for detecting a second distance to the ground, and
• wherein the layer thickness detecting device is fixedly secured to the screed.

The paver according to the invention is advantageous because the layer thickness detection device is fixedly attached to the screed, so that a more accurate detection of the layer thickness is made possible, since the measuring device is mounted at the point at which the actual installation takes place. The origin of a coordinate system for detecting the layer thickness is just at the point where the actual installation of the material takes place. Furthermore, the approach according to the invention facilitates installation, since the layer thickness detection device only has to be fastened to the screed, in particular no attachment to another area of the paver is required, which makes the measuring system e.g. due to the movement of the paver negatively affected.

According to embodiments, the film thickness detection device includes a signal processing unit configured to calculate the layer thickness of the built-in material layer based on the sensor signals from the first sensor and the second sensor, the distances of the first sensor and the second sensor from the screed trailing edge, and the mounting heights of the first Sensor and the second sensor with respect to the screed trailing edge to capture.

The inventive approach according to this embodiment is advantageous because only easily determinable variables are included in the calculation, namely the distance signals detected by the sensors and the well-defined distances of the sensors with respect to the screed trailing edge, so that in a simple manner with low signal processing effort exact determination of the layer thickness to the point where the installation of the layer takes place, namely with respect to the screed trailing edge, can be performed.

According to embodiments, the distances of the first sensor and the second sensor from the screed trailing edge and the attachment heights of the first sensor and the second sensor with respect to the screed trailing edge are the same, and the signal processing unit is configured to increase the layer thickness of the incorporated material layer based on the sensor signals from the screed first sensor and the second sensor, and to detect the mounting height of the first sensor and the second sensor with respect to the screed trailing edge.

The inventive approach according to this embodiment is advantageous since, assuming the same distances of the sensors with respect to the screed trailing edge, the determination of the layer thickness can be greatly simplified, in a first, good approximation for small changes in angle only the mounting height of the sensors and the sensor signals to be included in the calculation.

mit:

h_B =

Schichtdicke der eingebauten Materialschicht,

s₁ =

von dem ersten Sensor erfasster erster Abstand zu der eingebauten Materialschicht,

s₂ =

von dem zweiten Sensor erfasster zweiter Abstand zu dem Untergrund, und

B =

Anbringungshöhe des ersten Sensors und des zweiten Sensors in Bezug zu der Bohlenhinterkante.

The layer thickness of the incorporated material layer can be determined as follows: $$H_b={\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_2+s_1-2B$$

With:

h _B =

Layer thickness of the incorporated material layer,

s ₁ =

first distance to the built-in material layer detected by the first sensor,

s ₂ =

second distance to the ground detected by the second sensor, and

B =

Attachment height of the first sensor and the second sensor with respect to the screed trailing edge.

mit:

h_B =

Schichtdicke der eingebauten Materialschicht,

s₁ =

von dem ersten Sensor erfasster erster Abstand zu der eingebauten Materialschicht,

s₂ =

von dem zweiten Sensor erfasster zweiter Abstand zu dem Untergrund,

B =

Anbringungshöhe des ersten Sensors und des zweiten Sensors in Bezug zu der Bohlenhinterkante,

a =

Abstand des ersten Sensors von der Bohlenhinterkante, und

b =

Abstand des zweiten Sensors von der Bohlenhinterkante.

According to further embodiments, the mounting heights of the first sensor and the second sensor with respect to the screed trailing edge are the same, and the layer thickness of the incorporated material layer can be determined as follows: $$H_b={\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_2+\frac{b}{a}{s}_1-B\left(\frac{b}{a}+1\right)$$

With:

h _B =

Layer thickness of the incorporated material layer,

s ₁ =

first distance to the built-in material layer detected by the first sensor,

s ₂ =

second distance to the ground detected by the second sensor,

B =

Mounting height of the first sensor and the second sensor with respect to the screed trailing edge,

a =

Distance of the first sensor from the screed trailing edge, and

b =

Distance of the second sensor from the screed trailing edge.

The inventive approach according to this embodiment is advantageous because it allows a simple calculation of the layer thickness, the sensors can be arranged depending on the circumstances with different distances from each other with respect to the screed trailing edge, the calculation is simplified because the sensors are installed with the same height with respect to the screed trailing edge.

mit: $$c_1=\sqrt{a^2+B^2},$$

$$c_2=\sqrt{b^2+B^2},$$

$${\alpha }_1=\mathit{arcsin}\frac{B}{\sqrt{a^2+B^2}},$$

$${\alpha }_2=\mathit{arcsin}\frac{B}{\sqrt{b^2+B^2}},$$

h_B = Schichtdicke der eingebauten Materialschicht, s₁ = von dem ersten Sensor erfasster erster Abstand zu der eingebauten Materialschicht, s₂ = von dem zweiten Sensor erfasster zweiter Abstand zu dem Untergrund, B = Anbringungshöhe des ersten Sensors und des zweiten Sensors in Bezug zu der Bohlenhinterkante, a = Abstand des ersten Sensors von der Bohlenhinterkante, und b = Abstand des zweiten Sensors von der Bohlenhinterkante. According to further embodiments, the mounting heights of the first sensor and the second sensor with respect to the screed trailing edge are the same, and the layer thickness of the incorporated material layer can be determined as follows: $$H_b=s_2-{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\cdot \mathrm{<figure-callout\; id="2"\; label="sin\; \alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">sin\; </figure-callout>}\left[{\alpha }_{}\right]\left[{}_2+\left({\alpha }_1-\mathit{arcsin}\frac{s_1}{{\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_1}\right)\right]$$

With: $${\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_1=\sqrt{a^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}.$$

$$c_2=\sqrt{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">b</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}.$$

$${\mathrm{<figure-callout\; id="1"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_1=\mathit{arcsin}\frac{B}{\sqrt{a^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}}.$$

$${\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_2=\mathit{<figure-callout\; id="2"\; label="arcsin\; B\; b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">arcsin\; </figure-callout>}\frac{B}{\sqrt{b^{}}}\frac{\sqrt{{}^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}}{}.$$

h _B = Layer thickness of the incorporated material layer, s ₁ = first distance to the built-in material layer detected by the first sensor, s ₂ = second distance to the ground detected by the second sensor, B = Mounting height of the first sensor and the second sensor with respect to the screed trailing edge, a = Distance of the first sensor from the screed trailing edge, and b = Distance of the second sensor from the screed trailing edge.

The inventive approach according to this embodiment is advantageous because a highly accurate determination of the layer thickness is made possible, wherein an optimization of the calculation algorithm is achieved in that the pivot point of the measuring device is exactly assumed at the screed trailing edge.

The inventive approach according to this embodiment is advantageous because, due to the mounting of the sensors with a height with respect to the screed trailing edge, which is equal to the thickness of the screed, the determination of the mounting height is greatly simplified, for example, simply the known thickness or height of the screed as Mounting height without further steps to determine the same would be required.

In further embodiments, the mounting heights of the first sensor and the second sensor with respect to the screed trailing edge are the same, and the signal processing unit is configured to perform a calibration for determining the mounting height, wherein the first sensor detects the distance to the ground during the calibration.

The inventive approach according to this embodiment is advantageous because in a simple manner in a calibration process, the mounting heights of the first sensor and the second sensor, which are the same, can be determined by the first sensor in the calibration also the distance to the Underground recorded. According to the invention, a precise determination of the mounting height is thus made possible in a simple manner, which is also possible in the case of mounting the sensors at the level of the top of the screed, in order to determine the most accurate possible mounting height.

mit: s₁ = von dem ersten Sensor erfasster erster Abstand zu dem Untergrund, s₂ = von dem zweiten Sensor erfasster zweiter Abstand zu dem Untergrund, und B = Anbringungshöhe des ersten Sensors und des zweiten Sensors in Bezug zu der Bohlenhinterkante. The mounting height of the first sensor and the second sensor with respect to the screed trailing edge can be determined as follows: $$B=\frac{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_2+{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}{2}.$$

With: s ₁ = detected by the first sensor first distance to the ground, s ₂ = second distance to the ground detected by the second sensor, and B = Attachment height of the first sensor and the second sensor with respect to the screed trailing edge.

According to further embodiments, the layer thickness detection device comprises at least one carrier attached to the screed, wherein the first sensor is disposed on the carrier at a first distance from the screed trailing edge, and wherein the second sensor is disposed on the carrier at a second distance from the screed trailing edge is.

The inventive approach according to this embodiment is advantageous because using the carrier, the distance of the sensors with respect to the screed trailing edge can be adjusted easily, so that the first sensor safely scans the built-material layer and the second sensor safely scans the ground.

According to embodiments, the carrier comprises a measuring beam fixed to the screed, wherein the first sensor is disposed at a first end of the measuring beam at the first distance from the screed trailing edge, and wherein the second sensor is at a second end of the measuring beam at the second distance is arranged from the screed trailing edge.

According to embodiments, the measuring beam is rigid and immovably fixed to an upper side of the screed.

The use of a measuring beam according to this embodiment is advantageous, as this allows a simple attachment of the measuring arrangement to the screed, wherein in particular due to the fact that the measuring beam already comprises the respective sensors at its two ends, a simple attachment to the screed and in particular also a simple alignment of the sensors is ensured with respect to the screed. In other embodiments, it may be provided to arrange a plurality of such measuring bars with corresponding sensors along the width of the screed. Due to the rigid design of the measuring beam and the movable attachment of the same at the top of the screed a simple and reliable measurement is ensured.

According to further embodiments, the carrier comprises a first rigid carrier, which is immovably fixed to the screed and to which the first sensor is located at the first distance from the screed trailing edge, and a second rigid beam immovably fixed to the screed and to which the second sensor is located at the second distance from the screed trailing edge.

This exemplary embodiment is advantageous since, instead of a common measuring beam for fastening the two sensors, separate measuring beams or separate rigid supports can also be provided, depending on the circumstances, the first sensor and the second sensor at different positions with respect to the screed trailing edge and with respect to the screed trailing edge to arrange, for example, with different distances to the screed trailing edge and / or with different mounting heights.

According to embodiments, the first sensor and the second sensor include ultrasonic sensors, laser sensors, microwave sensors or a combination thereof.

• Erfassen eines ersten Abstands zu der eingebauten Materialschicht;
• Erfassen eines zweiten Abstands zu dem Untergrund umfasst; und
• Bestimmen der Schichtdicke der eingebauten Materialschicht basierend auf den erfassten ersten und zweiten Abständen, den Abständen eines ersten, fest an der Bohle des Straßenfertigers befestigten Sensors zum Erfassen des ersten Abstands und eines zweiten, fest an der Bohle des Straßenfertigers befestigten Sensors zum Erfassen des zweiten Abstands von der Bohlenhinterkante, und den Anbringungshöhen des ersten Sensors und des zweiten Sensors in Bezug zu der Hinterkante der Bohle des Straßenfertigers.

The present invention provides a method for detecting the thickness of a material layer built by a paver on a substrate, comprising the following steps:

• Detecting a first distance to the incorporated material layer;
• Detecting a second distance to the ground comprises; and
• Determining the layer thickness of the built-in material layer based on the detected first and second distances, the distances of a first, fixed to the screed of the paver sensor for detecting the first distance and a second, fixedly attached to the screed of the paver sensor for detecting the second distance from the screed trailing edge, and the mounting heights of the first sensor and the second sensor with respect to the trailing edge of the screed of the paver.

Thus, according to the invention, an approach is provided which enables a continuous determination of the layer thickness on a road paver, which represents one of the most important tasks for determining quality parameters during asphalt paving. Although the above-mentioned various measuring methods are known in the prior art in order to determine the layer thickness during asphalt paving, without, however, achieving an accuracy which is within an acceptable range which can be usefully used for the application. According to the invention, therefore, an approach is taught in which the layer thickness measurement uses a measuring method which has an increased accuracy, which is achieved in particular by providing a measuring device which is permanently installed on the screed.

Fig. 1

einen bekannten Straßenfertiger;

Fig, 2

einen Straßenfertiger gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;

Fig. 3

eine schematische Darstellung der Bohlengeometrie, wie sie beispielsweise bei einem Straßenfertiger, wie er in Fig. 2 gezeigt ist, verwendet wird;

Fig. 4

die Lage des XY-Koordinatensystems bezüglich der Bohlenhinterkante;

Fig. 5

das anhand der Fig. 4 erläuterte Koordinatensystem (XY-Koordinatensystem) mit einer Abstraktion der Größen für die Schichtdickenmessung;

Fig. 6

das in Fig. 3 gezeigte, nunmehr geneigte Bohlengeometrie;

Fig. 7

abstrakt die anhand der Fig. 6 erläuterten Messgrößen und deren geometrischen Zusammenhang;

Fig. 8

schematisch die geometrischen Kenngrößen, die zur Bestimmung der Schichtdicke mit erhöhter Genauigkeit herangezogen werden;

Fig. 9

eine schematische Bohlengeometrie ähnlich wie in Fig. 8, jedoch bei einer um den Winkel Δα gegenüber der Y-Achse verkippten Bohle;

Fig. 10

eine schematische Draufsichtdarstellung auf eine mögliche Installation des Schichtdickenmesssystems gemäß der vorliegenden Erfindung; und

Fig. 11

eine alternative Ausgestaltung der erfindungsgemäßen Messvorrichtung, bei der die Sensoren über getrennte, starre Träger an der Bohlenstruktur befestigt sind

Embodiments of the present invention will be explained in more detail with reference to the figures. Show it:

Fig. 1

a known paver;

Fig. 2

a paver according to an embodiment of the present invention;

Fig. 3

a schematic representation of the screed geometry, as for example in a paver, as in Fig. 2 shown is used;

Fig. 4

the location of the XY coordinate system with respect to the screed trailing edge;

Fig. 5

that on the basis of Fig. 4 explained coordinate system (XY coordinate system) with an abstraction of the sizes for the coating thickness measurement;

Fig. 6

this in Fig. 3 shown, now inclined plank geometry;

Fig. 7

abstract the basis of the Fig. 6 explained measurands and their geometric context;

Fig. 8

schematically the geometric parameters that are used to determine the layer thickness with increased accuracy;

Fig. 9

a schematic plank geometry similar to in Fig. 8 but at a plank tilted by the angle Δα with respect to the Y-axis;

Fig. 10

a schematic plan view of a possible installation of the layer thickness measuring system according to the present invention; and

Fig. 11

an alternative embodiment of the measuring device according to the invention, in which the sensors are attached via separate, rigid carrier to the plank structure

In the following description of exemplary embodiments of the invention, identical or equivalent elements are provided with the same reference numerals.

Fig. 2 shows a paver according to an embodiment of the present invention. The in Fig. 2 shown road paver is the in Fig. 1 However, the road paver shown in FIG. 1 similarly comprises the layer thickness detection device according to the invention. The in Fig. 2 paver shown does not include the in Fig. 1 shown ultrasonic sensors and the holder shown, instead, the layer thickness detection device according to the invention is attached to the screed 16. Alternatively, the in Fig. 1 shown sensors to control the installation of the material layer are maintained. At the in Fig. 2 In the embodiment shown, the layer thickness detection device according to the invention comprises a carrier 36, which is fixed rigidly and immovably to the upper side of the screed 16, so that the carrier 36 moves with the screed 16. At a first end of the carrier 36, a first sensor 38 is arranged at a distance a from the screed trailing edge 26 in the direction of travel behind the screed 16. At a second end of the carrier 36, a second sensor 40 is arranged at a distance b from the screed trailing edge 26 in the direction of travel in front of the screed 16, also an ultrasonic sensor or a laser sensor which generates a distance signal s2. The first sensor 38 may be an ultrasonic sensor, a laser sensor or a microwave sensor, and generates a distance signal s1 indicative of the distance from the first sensor 38 to the surface 42a of the built-in layer 42. The second sensor 40 may be an ultrasonic sensor, a laser sensor or a microwave sensor, and generates a distance signal s 2, which indicates the distance from the second sensor 40 to the substrate 14. The layer thickness detection device further comprises a signal processing device 44, which in Fig. 2 is shown schematically, and may be part of a control of the paver 10, for example. Alternatively, the signal processing device may also be provided independently of other elements of the paver. In the embodiment shown, the signal processing device 44 may be configured as a microcontroller, which receives data from the sensors 38 and 40 via schematically illustrated connections 46, 48, which reflect the measured distance s1 or s2. Based on the received distance signals s1 and s2 and based on the distances a, b of the sensors 38, 40 from the screed trailing edge 26 and based on the mounting height B of the sensors 38 and 40 relative to the screed trailing edge 26 and over the screed trailing edge 26, the signal processing means determines 44, the thickness h _B of the built-in layer 42. the signal processing means 44 may h _B detect continuously or at fixed predetermined time intervals, output and / or store the layer thickness, wherein the signal processing means may comprise a memory and / or a display for this purpose, further, the in Fig. 2 are not shown in detail.

At the in Fig. 2 illustrated embodiment, the carrier 36 is shown schematically and is rigidly and immovably attached to a plank top edge 16b, so that the carrier 36 and thus the sensors 38 and 40 move together with the plank, so by means of the manner explained in more detail below one in the Processing means 44, as mentioned above, the layer thickness h _{B of} the built-in layer 42 can be determined. In such a case, the mounting height of the sensors 38, 40 above the screed trailing edge 26 is a height equal to the thickness B and the height B of the screed 16, respectively.

The approach according to the invention for coating thickness measurement, for example when paving asphalt with the in Fig. 2 paver 10, based on the fact that the two height sensors 38, 40 are provided, which are arranged in a line along the direction of travel of the paver 10 and, according to one embodiment distance symmetrically to the screed trailing edge 26 so that the sensor 38, the distance s1 to the asphalt surface 42a the built-in asphalt layer 42 measures, and that the sensor 40 measures the distance s2 to the substrate 14. The two sensors 38, 40 are rigidly connected to the paver 16, by means of the carrier 36, in particular so that only slight twisting can occur.

The following is based on the Fig. 3 the inventive approach for determining the layer thickness according to a first embodiment explained in more detail. Fig. 3 shows a schematic representation of the screed geometry, such as in a road paver, as in Fig. 2 is shown, but can also be used in other road pavers. Fig. 3 shows the schematic structure for the layer thickness measurement using the distance sensors 38 and 40 and on the basis of the associated distance measured values s1 and s2. In Fig. 3 a symmetry point S is shown, which is located directly above the screed trailing edge 26, and that of the in Fig. 3 is traversed line L1 shown. According to the embodiment shown, the sensors 38, 40, as mentioned above, are rigidly connected to the paver 16 via the carrier 36, in such a way that no twists are made in the direction of the imaginary line L1, in particular no twists in the vertical direction. The distance B, which indicates the mounting height of the sensors with respect to the screed trailing edge 26, lies between the point of symmetry S and the surface 42 a of the installed asphalt layer 42. The distance B represents in the embodiment shown approximately a constant value, even if the screed 16 via the traction point 20 is moved in the longitudinal inclination. The line L1 represents a reference line for the sensors 38 and 40, and at the same time the mounting height with respect to the point of symmetry S. In this connection, the line L1 may also be referred to as a mounting reference line. The distances a and b are the distances or installation distances of the sensors 38 and 40 relative to the screed trailing edge 26 and to the point of symmetry S. Das Coordinate system for layer thickness measurement using sensors 38 and 40 is located directly on the screed trailing edge 26 as shown in FIG Fig. 4 is clarified, which represents the position of the XY coordinate system with respect to the screed trailing edge 26. More specifically, the Y-origin of the coordinate system lies directly on the screed trailing edge 26, with the scrape edge defining the X origin. The coordinate system follows the movement of the screed trailing edge 26 during the paving process, where the X axis coincides negatively with the road surface 42a in its extension from zero.

For the derivation of the calculation equation for the layer thickness h _B used according to the first exemplary embodiment, reference is made below to FIG Fig. 5 Reference is made, which is an abstraction of the measured quantities for the coating thickness measurement. In Fig. 5 is that on the basis of Fig. 4 illustrated coordinate system (XY coordinate system) shown, as well as the thickness h _{B of} the built-in layer 42 and the distance measurements s1 and s2 of the sensors, which in Fig. 2 have been explained, the distances with respect to the asphalt surface 42a and with respect to the substrate 14, starting from the line L1, which is spaced from the zero point of the coordinate system by the installation height B of the sensors in the positive Y direction. In the embodiment just described, it is assumed that the sensors 38 and 40 each have the same distance to the zero point, ie have the same distance along the X direction to the zero point in terms of absolute value. On the basis of the basis of the FIGS. 3 to 5 described geometry, the layer thickness h _B can be determined according to the embodiment described as follows: $$H_B={\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_2+s_1-2B$$

• die Abstände a, b der Sensoren 38, 40 zur Bohlenhinterkante 26 (zum Symmetriepunkt S) sind gleich, d.h. a = b
• die Sensoren 38 und 40 befinden sich auf der gedachten Linie L1 und sind starr mit der Bohle 16, beispielsweise mittels des Trägers 36, verbunden,
• der Sensor 38 misst den Abstand s1 zur Asphaltoberfläche 42a
• der Sensor 40 misst den Abstand s2 zum Untergrund 14,
• der Abstand B ist konstant und stellt die Entfernung zwischen der Linie L1 und der Hinterkante 26 der Bohle 16 in Y-Richtung dar, und
• die Linie L1 verläuft zunächst parallel zum Untergrund 14.

If the inclination of the reference line L1 changes (see Fig. 3 ) symmetrically about the Y-coordinate axis, the equation given above essentially retains its validity, since the sum of the signals s1 + s2 remains approximately constant, as will be explained in more detail below. The derivation of the above equation (1) is explained in more detail below, wherein according to the illustrated embodiment, the following assumptions are made:

• the distances a, b of the sensors 38, 40 to the screed trailing edge 26 (to the point of symmetry S) are equal, ie a = b
• the sensors 38 and 40 are located on the imaginary line L1 and are rigidly connected to the screed 16, for example by means of the carrier 36,
• the sensor 38 measures the distance s1 to the asphalt surface 42a
• the sensor 40 measures the distance s 2 to the ground 14,
• the distance B is constant and represents the distance between the line L1 and the trailing edge 26 of the plank 16 in the Y direction, and
• the line L1 initially runs parallel to the ground 14.

From the Fig. 5 On the basis of the above assumptions, the layer thickness can be read directly according to the following equation: $$H_B=s_2-{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_1=s_2-B$$

Due to a movement of the screed, it can now come to an inclination of the line L1, wherein a change in the inclination of the measuring system based on the Fig. 6 is shown. By changing the position or the inclination of the line L1 to the line L1 ', symmetrically about the point of symmetry S, for example due to a change in the Bohlenanstellwinkels, as in Fig. 6 is shown, the measured values s1 and s2 will change symmetrically by Δs1 and Δs2. In order for the equation (2) to remain valid, the line L1 'must again be aligned parallel to the ground 14, which is achieved by rotating the line L1' by the values Δs1 and Δs2 relative to the point of symmetry S, as shown by the arrows 50a and 50b in FIG Fig. 6 is shown. If one then corrects the value s2 ', which is the measured value which is detected by the sensor 40 at the changed bottom inclination, by Δs2, then one obtains again the original measured value s2, ie the measured value which is for the imaginary and parallel to the background 14 (coordinate axis X) extending line L1 would result. The value .DELTA.s2, however, can not be measured directly and is merely an auxiliary quantity that can be resolved in the equation system. The Fig. 7 Abstract illustrates the basis of the Fig. 6 explained measurands and their geometric context. The above-mentioned relationship between the measured value s2 'actually measured by the sensor 40 and the original measured value s2 detected at the horizontal line L1 is as follows: $$s_2=s_2^{\text{'}}-{\mathrm{<figure-callout\; id="2"\; label="\Delta \; s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}\mathit{s}\mathit{}}_2$$

Substituting equation (3) into equation (2), one obtains: $$H_B=s_2-B=s_2^{\text{'}}-{\mathrm{\Delta }\mathit{s}}_2-B$$

The value Δs2, which is not directly measurable as mentioned above, will now be described using the measured value s1 'of the first sensor 38 and the mounting height B, as shown in FIG Fig. 7 results, for reasons of symmetry the following applies: $${\mathrm{\Delta }\mathit{s}}_2={\mathrm{\Delta }\mathit{s}}_1=B-s_1^{\text{'}}$$

Substituting equation 5 into equation 4, one obtains: $$H_B=s_2^{\text{'}}-\left(B-s_1^{\text{'}}\right)-B$$

After dissolving results then: $$H_B=s_2^{\text{'}}+s_1^{\text{'}}-2B$$

In equation (7), s1 'and s2' are the distances measured by the sensors, and by generalizing the measured values s1 'and s2' to the measured values s1 and s2, equation 1 results, namely $$H_B={\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_2+s_1-2B$$

According to the invention, the layer thickness is thus obtained according to the illustrated embodiment by adding the measured values obtained from the sensors and the subtraction of the double constant B, as stated above. Thus, according to the exemplary embodiment, a simple calculation rule is provided which enables a layer thickness determination with high accuracy with a simple mechanical design of the measuring device and with a simple calculation algorithm.

In the embodiments described above, it was assumed for the sake of simplicity that the distances of the sensors 38, 40 from the screed trailing edge 26 are the same, but this is not absolutely necessary, and in particular depending on conditions that may be predetermined by the construction of the paver, also can not be possible. However, the approach according to the invention equally applies to an asymmetrical structure in which the distances a and b of the sensors 38 and 40 from the screed trailing edge 26 are different. In this case, only a correction of above correction quantities Δs2 and Δs1 are carried out after the set of rays, and there is the following relationship: $$\frac{{\mathrm{\Delta }\mathit{s}}_1}{a}=\frac{{\mathrm{\Delta }\mathit{s}}_2}{b}$$

From equation (9) follows: $${\mathrm{\Delta }\mathit{s}}_2=\frac{b}{a}\cdot {\mathrm{\Delta }\mathit{s}}_1$$

woraus sich nach Auflösung die Schichtdicke wie folgt ergibt: $$h_B=s_2+\frac{b}{a}{s}_1-B\left(\frac{b}{a}+1\right)$$

Performing the above derivation of equations 3 through 8 again, now using Equation 9, one obtains: $$H_B=s_2-\left(\frac{b}{a}\cdot \left[B-s_1\right]\right)-B$$

resulting in the layer thickness after dissolution as follows: $$H_B={\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_2+\frac{b}{a}{s}_1-B\left(\frac{b}{a}+1\right)$$

In Equation 11, the constant B represents the mounting height of the sensors 38 and 40 with respect to the screed trailing edge 26, as described above with reference to FIGS Figures 3 and 5 has been explained, wherein in the preferred embodiments, the constant B is equal to the height of the screed. In other embodiments, the attachment of the carrier may be at a distance from the top of the screed 16a, so that here the constant B indicates the thickness of the screed and the additional distance of the carrier over the screed. In yet other embodiments, the mounting height of the sensors 38 and 40 with respect to the screed trailing edge 26 may be less than the screed thickness.

According to exemplary embodiments, it is possible to carry out a calibration of the system before starting the installation in order to determine the constant B for the subsequent determination of the layer thickness reliably. Starting from equation 1, the constant B can be calculated as follows: $$B=\frac{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_2+s_1-{\mathrm{<figure-callout\; id="2"\; label="H\; B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">H\; </figure-callout>}}_B}{2}$$

This constant can be determined during a system calibration and remains stored as a constant parameter in the coating thickness measurement system. As part of the system calibration, which is performed prior to the actual installation of the layer 42, a measurement by means of the sensors 38 and 40, which now both refer to the substrate 14, since due to the missing layer 42, the layer thickness given in equation 12 to zero so that as part of the system calibration the constant B can be determined as follows: $$B=\frac{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_2+{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">s</figure-callout>}}_1}{2}$$

The embodiments described above represent a first, good approximation for the layer thickness calculation, which provides very good and accurate results, especially for small changes in angle, as corresponding test series and tests show. Furthermore, this simplified approach is suitable for determining the constant B as part of a system calibration. Embodiments are described below in which an even more accurate calculation of the layer thickness is made possible, wherein for further optimization, starting from the first embodiment described above, the pivot point of the measuring device is assumed exactly at the screed trailing edge 26. Fig. 8 schematically shows the geometric characteristics that are used to determine the layer thickness with increased accuracy. In Fig. 8 is the point of symmetry S, which was assumed in the simplified calculation at the top of the screed, namely, where the carrier is attached, now assumed at the screed trailing edge 26. This results in that the sensors 38, 40 perform a kind of pivoting movement which does not lead to a symmetrical change in position of the sensors 38, 40 with respect to the in Fig. 4 shown Bohlenkoordinatensystems leads. As based on the Fig. 4 As has already been explained, the coordinate system for calculating the layer thickness relates to the screed trailing edge and the newly laid asphalt layer 42, with the peak of the coordinate system at the screed trailing edge 26 and the X axis lying in the surface 42a of the already laid asphalt layer. The coordinate system determined in this way is called the screed coordinate system, which is defined during installation. However, the screed 16 may change during installation even in their position in the coordinate system depending on the screed angle.

$$c_2=\sqrt{b^2+B^2}$$

In the Fig. 8 are given various constant characteristics, which in the layer thickness determination according to the invention according to the embodiment for a highly accurate Calculation of the layer thickness are used. Fixed are the sizes a, b and B, namely the distances between the sensors 38 and 40 of the screed trailing edge 26 and the mounting height with respect to the screed trailing edge 26. Using these fixed sizes, the in Fig. 8 and the variables a1 'and a2', which will be explained later, where C1 and C2 result as follows: ## EQU1 ## $$c_{}$$$${}_1=\sqrt{a^2+B^2}$$

$$c_2=\sqrt{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">b</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}$$

$${\alpha }_2=\mathit{arcsin}\frac{B}{c_2}$$

In the Fig. 8 shown angles α1 and α2 are as follows: $${\mathrm{<figure-callout\; id="1"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_1=\mathit{<figure-callout\; id="1"\; label="arcsin\; B\; c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">arcsin\; </figure-callout>}\frac{B}{c_{}}\frac{{}_1}{}$$

$${\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_2=\mathit{<figure-callout\; id="2"\; label="arcsin\; B\; c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">arcsin\; </figure-callout>}\frac{B}{c_{}}\frac{{}_2}{}$$

$${\alpha }_2=\mathit{arcsin}\frac{B}{\sqrt{b^2+B^2}}$$

Taking into account the known values a, b and B, the angles are as follows: $${\mathrm{<figure-callout\; id="1"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_1=\mathit{arcsin}\frac{B}{\sqrt{a^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}}$$

$${\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_2=\mathit{<figure-callout\; id="2"\; label="arcsin\; B\; b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">arcsin\; </figure-callout>}\frac{B}{\sqrt{b^{}}}\frac{\sqrt{{}^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}}{}$$

Fig. 9 shows the schematic plank geometry similar to in Fig. 8 , but at a by the angle .DELTA..alpha. with respect to the Y-axis tilted screed, from which the already mentioned above and in Fig. 9 angles a1 'and a2' shown, wherein for any measured value s1 the angle a1 'is calculated as follows: $${\alpha }_1^{\text{'}}=\mathit{arcsin}\frac{s_1}{{\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_1}$$

From α1 'and α1, the angle of rotation Δα can be determined as follows: $$\mathrm{\Delta }\mathit{\alpha }={\alpha }_1-{\alpha }_1^{\text{'}}$$

If one considers B, C1 and C2 as position vectors, then this angle of rotation Δα acts in the same way on these position vectors, so that the following relationship results for a2 ': $${\alpha }_2^{\text{'}}={\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_2+\mathrm{\Delta }\mathit{\alpha }$$

für h_x gilt: $$h_B=s_2-c_2\cdot {\sin \alpha }_2^{\prime }=s_2-c_2\cdot \sin \left({\alpha }_2+\mathrm{\Delta }\mathit{\alpha }\right)$$

so dass sich für die Schichtdicke die folgende Berechnungsgrundlage ergibt: $$h_B=s_2-c_2\cdot \sin \left[{\alpha }_2+\left({\alpha }_1-\mathit{arcsin}\frac{s_1}{c_1}\right)\right]$$

mit: $$c_1=\sqrt{a^2+B^2}$$

$$c_2=\sqrt{b^2+B^2}$$

$${\alpha }_1=\mathit{arcsin}\frac{B}{\sqrt{a^2+B^2}}$$

$${\alpha }_2=\mathit{arcsin}\frac{B}{\sqrt{b^2+B^2}}$$

wobei B bekannt ist, beispielsweise durch die oben erwähnte Kalibrierung.From the Fig. 8 can be derived for the layer thickness h _{B the} following equation: $$H_B=s_2-H_x$$

for h _x applies: $$H_B=s_2-{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\cdot {\sin \alpha }_2^{\text{'}}=s_2-{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\cdot \mathrm{<figure-callout\; id="2"\; label="sin\; \alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">sin\; </figure-callout>}\left({\alpha }_{}\right)\left({}_2+\mathrm{\Delta }\mathit{\alpha }\right)$$

so that the following calculation basis results for the layer thickness: $$H_B=s_2-{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\cdot \mathrm{<figure-callout\; id="2"\; label="sin\; \alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">sin\; </figure-callout>}\left[{\alpha }_{}\right]\left[{}_2+\left({\alpha }_1-\mathit{arcsin}\frac{s_1}{{\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_1}\right)\right]$$

With: $${\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">c</figure-callout>}}_1=\sqrt{a^2+B^2}$$

$$c_2=\sqrt{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">b</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}$$

$${\mathrm{<figure-callout\; id="1"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_1=\mathit{arcsin}\frac{B}{\sqrt{a^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}}$$

$${\mathrm{<figure-callout\; id="2"\; label="\alpha "\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_2=\mathit{<figure-callout\; id="2"\; label="arcsin\; B\; b"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">arcsin\; </figure-callout>}\frac{B}{\sqrt{b^{}}}\frac{\sqrt{{}^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="imgf0002.png,imgf0003.png"\; state="\{\{state\}\}">B</figure-callout>}}^2}}{}$$

where B is known, for example by the calibration mentioned above.

The abovementioned embodiments of the layer thickness detection approach according to the invention are advantageous over conventional approaches, since the measurement setup according to the invention is mounted in a particularly simple manner on the screed 16 (see FIG Figures 2 and 3 ) is installed, and according to embodiments, for example, in an existing leveling system can be integrated. The distance of the sensors with respect to the screed trailing edge can be equal to the thickness of the screed according to a preferred embodiment, so that it requires no additional installation structures, but the measuring structure according to the invention can be easily attached to the existing screed. Equally advantageous may be to adjust a certain distance of the ultrasonic sensors from the surface to be detected in order to obtain an optimal measuring distance.

According to preferred embodiments, the sensors are mounted as symmetrically as possible to the screed trailing edge, so that when using the calculation rule according to the first embodiment sufficiently accurate results, without the use of highly accurate calculation algorithm is required. According to embodiments, it can be provided that the calculation algorithm according to the invention implements both the first algorithm and the second, more accurate algorithm, wherein, for example, depending on a detected adjustment of the screed, for example, when exceeding a critical angle, or if very accurate results are desired, the calculation of the layer thickness from the first algorithm to the second, more accurate algorithm.

Furthermore, in embodiments of the invention, it may be provided to use the data recorded by the layer thickness measuring device regarding the layer thickness for active control of the paver with respect to a position of the screed in order to maintain a predetermined layer thickness.

Hereinafter, exemplary embodiments are described which indicate the manner in which the installation of the sensors can take place. Fig. 10 shows a schematic plan view of a possible installation of the layer thickness measuring system according to the present invention. As in Fig. 10 2, the system includes two beams or measuring beams 36a, 36b secured to the screed 16, either on the screed top 16b or spaced upwardly from the screed top, with respective first sensors 38a, 38b and second sensors 40a, 40b the respective ends of the measuring beam 36a, 36b are arranged with the distances a, b to the screed trailing edge 26. In addition to the in Fig. 10 of course, only one measuring bar, but also more than two measuring bars with correspondingly arranged sensor systems can be provided, whereby the scanning area for the layer thickness measurement increases due to the plurality of sensors, so that a higher measured value accuracy is established.

Fig. 11 shows an alternative embodiment of the measuring device according to the invention, in which the sensors 38 and 40 via separate, rigid support 36a, 36b are attached. As mentioned above, it is essential that the calculation algorithm be aware of the Mounting heights of the sensors 38 and 40 has, which may also be different, as in Fig. 11 Unlike in the embodiments described above, in which the sensors 38, 40 are arranged at opposite ends of a carrier or measuring beam, is in the in Fig. 11 shown embodiment, to arrange the sensor 38 higher than the sensor 40, via a rigid, attached to the plank top edge 16b support 36a, wherein the attachment 36a is such that the sensor 38 moves together with the screed 16, preferably so, that no connections occur. The sensor 40 is attached to the pull arm 18 that rotates the screed 16 via a second support structure 36b such that both the sensor 38 and the sensor 40 are disposed in a fixed, well-defined and non-changing relationship with the screed trailing edge 26 is, so that the above-described approaches for determining the layer thickness of the built-in layer 42 also in an embodiment according to Fig. 11 can be used, in which case then additionally the different heights of the sensors 38 and 40 must be considered.

The above-described sensors may preferably be ultrasonic sensors, but laser scanners may also be used which then provide orthogonal vectors to the substrate or to the layer 42 for calculating the layer thickness. Other sensor configurations may include a combination of ultrasonic sensors and laser scanners, whereby only a simple laser distance measurement at both measuring positions is possible.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

Depending on particular implementation requirements, embodiments of the invention may be implemented in hardware or in software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-ray Disc, a CD, a ROM, a PROM, an EPROM, a EEPROM or a FLASH memory, a hard disk or other magnetic or optical storage are stored on the electronically readable control signals that can cooperate with a programmable computer system or cooperate, that the respective method is performed. Therefore, the digital storage medium can be computer readable. Thus, some embodiments according to the invention include a data carrier having electronically readable control signals capable of interacting with a programmable computer system such that one of the methods described herein is performed.

In general, embodiments of the present invention may be implemented as a computer program product having a program code, wherein the program code is operable to perform one of the methods when the computer program product runs on a computer. The program code can also be stored, for example, on a machine-readable carrier.

Other embodiments include the computer program for performing any of the methods described herein, wherein the computer program is stored on a machine-readable medium.

In other words, an embodiment of the method according to the invention is thus a computer program which has a program code for performing one of the methods described herein when the computer program runs on a computer. A further embodiment of the inventive method is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program is recorded for carrying out one of the methods described herein.

A further embodiment of the method according to the invention is thus a data stream or a sequence of signals, which represent the computer program for performing one of the methods described herein. The data stream or the sequence of signals may be configured, for example, to be transferred via a data communication connection, for example via the Internet.

Another embodiment includes a processing device, such as a computer or a programmable logic device, that is configured or adapted to perform one of the methods described herein.

Another embodiment includes a computer on which the computer program is installed to perform one of the methods described herein.

In some embodiments, a programmable logic device (eg, a field programmable gate array, an FPGA) may be used to perform some or all of the functionality of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor to perform one of the methods described herein. In general, in some embodiments, the methods are performed by any hardware device. This may be a universal hardware such as a computer processor (CPU) or hardware specific to the process, such as an ASIC.

The embodiments described above are merely illustrative of the principles of the present invention. It will be understood that modifications and variations of the arrangements and details described herein will be apparent to others of ordinary skill in the art. Therefore, it is intended that the invention be limited only by the scope of the appended claims and not by the specific details presented in the description and explanation of the embodiments herein.

Claims (13)

Road paver, with: a screed (16) for installing a layer of material (42) on a substrate (14); a layer thickness detecting device for detecting the thickness (h _B ) of the built-in material layer (42), wherein the layer thickness detection device includes a first sensor (38) in the direction of travel behind the screed (16) for detecting a first distance to the built-in material layer (42) and a second sensor (40) in the direction of travel in front of the screed (16) for detecting a second distance the background (14), and wherein the layer thickness sensing device comprises at least one support rigidly and immovably attached to the screed (16) such that the layer thickness sensing device is fixedly secured to the screed, the first sensor (38) being secured to the support a first distance from the screed trailing edge (26 ), and wherein the second sensor (40) is disposed on the carrier at a second distance from the screed trailing edge (26); and the layer thickness detection device comprising a signal processing unit (44), characterized in that the signal processing unit (44) is configured to determine the layer thickness (h _B ) of the incorporated material layer (42) based on the sensor signals (s ₁ , s ₂ ) from the first sensor (38) and the second sensor (40) (a, b) of the first sensor (38) and the second sensor (40) from the screed trailing edge (26), and the mounting heights of the first sensor (38) and the second sensor (40) with respect to the screed trailing edge (26) to capture. Road paver according to claim 1, wherein
the distances (a, b) of the first sensor (38) and the second sensor (40) from the screed trailing edge (26) are equal,
the mounting heights of the first sensor (38) and the second sensor (40) are equal with respect to the screed trailing edge (26), and
the signal processing unit (44) is configured to determine the layer thickness (h _B ) of the incorporated material layer (42) based on the sensor signals (s ₁ , s ₂ ) from the first sensor (38) and the second sensor (40) and Attachment height of the first sensor (38) and the second sensor (40) with respect to the screed trailing edge (26) to detect. Road paver according to claim 2, wherein the layer thickness (h _B ) of the built-in material layer (42) is determined as follows: $$H_B=s_2+s_1-2B$$

With: h _B = Layer thickness of the incorporated material layer (42), s ₁ = first distance to the built-in material layer (42) detected by the first sensor (38), s ₂ = from the second sensor (40) detected second distance to the ground (14), and B = Mounting height of the first sensor (38) and the second sensor (40) with respect to the screed trailing edge (26). Road paver according to claim 1, wherein
the mounting heights of the first sensor (38) and the second sensor (40) are equal with respect to the screed trailing edge (26), and
the layer thickness (h _B ) of the incorporated material layer (42) is determined as follows: $$H_B=s_2+\frac{b}{a}{s}_1-B\left(\frac{b}{a}+1\right)$$

With: h _B = Layer thickness of the incorporated material layer (42), s ₁ = first distance to the built-in material layer (42) detected by the first sensor (38), s ₂ = second distance to the background (14) detected by the second sensor (40), B = Mounting height of the first sensor (38) and the second sensor (40) with respect to the screed trailing edge (26), a = Distance of the first sensor (38) from the screed trailing edge (26), and b = Distance of the second sensor (40) from the screed trailing edge (26). Road paver according to claim 1, wherein
the mounting heights of the first sensor (38) and the second sensor (40) are equal with respect to the screed trailing edge (26), and
the layer thickness (h _B ) of the incorporated material layer (42) is determined as follows: $$H_B=s_2-c_2\cdot \sin \left[{\alpha }_2+\left({\alpha }_1-\mathit{arcsin}\frac{s_1}{c_1}\right)\right]$$

With: $$c_1=\sqrt{a^2+B^2}$$

$$c_2=\sqrt{b^2+B^2}$$

$${\alpha }_1=\mathit{arcsin}\frac{B}{\sqrt{a^2+B^2}}$$

$${\alpha }_2=\mathit{arcsin}\frac{B}{\sqrt{b^2+B^2}}$$

h _B = Layer thickness of the incorporated material layer (42), s ₁ = first distance to the built-in material layer (42) detected by the first sensor (38), s ₂ = second distance to the background (14) detected by the second sensor (40), B = Mounting height of the first sensor (38) and the second sensor (40) with respect to the screed trailing edge (26), a = Distance of the first sensor (38) from the screed trailing edge (26), and b = Distance of the second sensor (40) from the screed trailing edge (26). A paver according to any one of claims 1 to 5, wherein the mounting height of the first sensor (38) and the second sensor (40) with respect to the screed trailing edge (26) is equal to the thickness of the screed (16). Road paver according to one of claims 1 to 6, wherein
the mounting heights of the first sensor (38) and the second sensor (40) are equal with respect to the screed trailing edge (26), and
the signal processing unit (44) is configured to perform a calibration for determining the mounting height, wherein the first sensor (38) detects the distance to the ground (14) during the calibration. The paver of claim 7, wherein the signal processing unit (44) is configured to determine the mounting height of the first sensor (38) and the second sensor (40) relative to the screed trailing edge (26) as follows: $$B=\frac{s_2+s_1}{2}$$

With: s ₁ = first distance to the substrate (14) detected by the first sensor (38), s ₂ = from the second sensor (40) detected second distance to the ground (14), and B = Mounting height of the first sensor (38) and the second sensor (40) with respect to the screed trailing edge (26). A paver according to any one of claims 1 to 8, wherein the carrier comprises a measuring beam fixed to the screed (16),
wherein the first sensor (38) is disposed at a first end of the measuring beam at the first distance from the screed trailing edge (26), and
wherein the second sensor (40) is disposed at a second end of the measuring beam at the second distance from the screed trailing edge (26). Road paver according to claim 9, wherein the measuring beam is rigid and is immovably fixed to an upper side of the screed (16). A paver according to claim 8, wherein the carrier comprises a first rigid support immovably secured to the screed (16) and having the first sensor (38) spaced the first distance from the screed trailing edge (26) and a second rigid one A carrier immovably fixed to the screed (16) and to which the second sensor (40) is disposed at the second distance from the screed trailing edge (26). A paver according to any one of claims 1 to 11, wherein the first sensor (38) and the second sensor (40) comprise ultrasonic sensors, laser sensors or microwave sensors or a combination thereof. Method for detecting the thickness (h _B ) of a material layer (42) installed by a road paver (10) with a screed (16) on a substrate (14) through a layer thickness detection device with a first sensor (38) in the direction of travel behind the screed (16 ) for sensing a first distance to the built-in material layer (42) and a second sensor (40) in the direction of travel in front of the screed (16) for detecting a second distance to the ground (14), the layer thickness sensing device comprising at least one beam that is rigid and immovably fixed to the screed (16) such that the layer thickness sensing device is fixedly secured to the screed, the first sensor (38) being disposed on the carrier a first distance from the screed trailing edge (26), and the second sensor (16) 40) is disposed on the carrier at a second distance from the screed trailing edge (26), and wherein the method comprises the steps of: Detecting a first distance to the built-in material layer (42); Detecting a second distance to the ground (14); and Determining the layer thickness (h _B ) of the incorporated material layer (42); characterized in that the layer thickness (h _B ) based on the detected first and second distances, the distances (a, b) of the first sensor (38) and the second sensor (40) from the screed trailing edge (26), and mounting heights of the first sensor (38 ) and the second sensor (40) relative to the plank edge.

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